Most of the shock devices of the shock sensors of the conventional burglar alarms adjust the sensitivity of the shock device through control circuits. In this kind of shock device of shock sensors of the burglar alarms, the control circuits can only be set to an optimum condition in a factory where they are produced. The control circuits tend to be inaccurate because of the moisture and dust encountering the control circuits after the circuits are produced. This requires readjustment for the control circuits after they have been used for a while. It is not easy for the users to do the readjustments for the control circuits and thus the performance of the burglar alarms become more and more unsatisfactory.
Recent conventional shock sensors utilize electronic control circuits, which are fixed after being produced, incorporating shock sensors which are highly controlled. It is not easy for the characteristics of the shock sensors to be influenced by external environment because the shock sensors are of mechanical structures. However, the mechanical shock sensors tend to suffer from irresistable changes of stress. Therefore, many manufacturers of burglar alarms try to improve shock sensors. The present invention improves a kind of popular conventional shock device of a shock sensor of a burglar alarm, which is shown in FIGS. 1 and 2. The conventional shock device includes mainly an ".hoarfrost." shaped enclosure 1. An inductance coil 11 is provided on the central lower portion of the enclosure 1. A resilient rubber element 12 having a cylindrical cup 121 at the center thereof is provided in the enclosure 1. A permanent magnet 122 is installed in the cylindrical cup 121, with the magnet 122 facing the inductance coil 11 in the enclosure 1. Cylindrical ends 123 and 124 are provided on two sides of the rubber element 12, respectively, for fixing the rubber element 12 on two fixing posts 13 and 14 in the enclosure 1. The rubber element 12 has two arms 125 and 126. The magnet 122 is of some distance from the fixing posts 13 and 14 and the arms 125 and 126 are resilient. Therefore, the magnet 122 can move up and down as well as leftwardly and rightwardly repeatedly when there is a shock to the shock device. However, this shock device suffers from the following drawbacks:
(1) The structural shape of the enclosure 1 of this conventional shock device is complicated and needs high stability. The elements such as the rubber element 12 and the inductance coil 11 must be installed in the enclosure 1 stably, symmetrically, and without any inclination. This makes the production and the assembling difficult. PA0 (2) The enclosure 1 can not be deformed, even slightly, otherwise it would be difficult to be repaired. Besides, it is easy for defects in the device to occur during production because higher standards must be met for the enclosure 1 to function properly. Thus, it is difficult to do quality control. PA0 (3) It is difficult to adjust and set the rubber element 12 to its proper position during assembly. Therefore, this is time consuming and the cost thereof is increased. PA0 (4) In the conventional shock sensor, the magnet 122 on the rubber element 12 will be moved when there is a vibration caused to the shock sensor. Thus, signals will be generated on the inductance coil 11 in the enclosure 1 because there is an altering of magnetic flux by the magnet 122. However, after a period of use, the rubber element 12 will be aging and degrade rapidly. This causes an unsatisfactory product.
The present invention mitigates the drawbacks of the above-mentioned shock sensor and provides a more effective shock device of a shock sensor of a burglar alarm.
The present invention shall be described in detail with reference to the drawings. These descriptions are provided for better understanding of the present invention and should not be construed as limitations of the scope of the present invention.